Large Animal Extinction During Ice Age Was Caused By Humans, Not Climate Change: Scientists

While history might have been inclined to blame the mass extinction of some of the Earth's mightiest mammals on climate change, scientists suggest a likelier culprit.

Us.

For decades, the circumstances surrounding the disappearance of large mammals — some 177 species vanished in the wake of the last Ice Age — has been hotly contested.

Dubbed megafauna, the list of the missing is staggering. According to scientists at Denmark's Aarhus University, woolly mammoths, forest elephants, giant deer and even some species of giant sloths are among the missing — representing big mammals from almost every climate zone.

Skeleton of Megatherium, extinct giant ground sloth of South America: herbivore. This specimen found in Paraguay c1796. Lithograph published London 1823 (Photo by Universal History Archive/Getty Images)

Not so, Danish researchers contend in a freshly published research paper.

“Our results strongly underline the fact that human expansion throughout the world has meant an enormous loss of large animals,” notes Søren Faurby, a postdoctorate researcher at Aarhus.

The researchers point out that periods of dramatic climate swings characterized each Ice Age, with the most recent epoch spanning from around 110,000 to 12,000 years ago. What puzzled scientists, however, was the absence of mass extinctions during previous Ice Ages.

"The significant loss of megafauna all over the world can therefore not be explained by climate change, even though it has definitely played a role as a driving force in changing the distribution of some species of animals," suggests Aarhus researcher Christopher Sandom.

"Reindeer and polar foxes were found in Central Europe during the Ice Age, for example, but they withdrew northwards as the climate became warmer."

Story continues after slideshow.

PHOTOS: GIANT PREHISTORIC ANIMALS, 'MEGAFAUNA'

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Extinct Prehistoric Animals

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This North American bird, which stood over 8 feet tall, would have had an enormous, axe-like beak.

This heavily-armored predator had the second most powerful bite of any fish.

The hornless rhinoceros-like creatures of this genus were the largest land mammals of all time.

Giant ground sloths of this genus were about the size of today's elephants. The megatherium only went extinct around 10,000 years ago (right around the time when humans started farming), and smaller relatives may have survived as late as the 16th century!

Richard Owen, director of London's Museum of Natural History, stands next to the largest of all moa. Moa, which originated in New Zealand, were flightless, and some were even wingless.

The Argentavis magnificens, an early relative of the Andean Condor, was the largest flying bird ever discovered.

These creatures, the largest marsupials that ever lived, roamed Australia. Some scientists have suggested that stories of the supernatural 'bunyip' creature in Aboriginal folklore could be based on diprotodonts.

These distant relatives of modern elephants had an imposing appearance, with strange, downward-curving tusks and heights of up to 16 feet at the shoulder.

The fearsome Liopleuredon, right, had a jaw nearly ten feet long. The Leedsichthys, left, was a bony fish that may have been even larger than it looked; some estimates put its maximum length at 53 feet.
Correction: An earlier version of this slide had the positions of the Liopleuredon and Leedsichthys reversed.

So why did the last swing of the climate pendulum coincide with the ravaging of Earth's big mammals?

Well, it may have something to do with a relatively new animal on the block.

What we regard as modern man first appeared in Africa, before touching down on fresh continents — a migration that only really took hold over the last 100,000 years.

The Danish study, hailed as the first worldwide analysis of large animals living between 132,000 and 1,000 years ago, found a compelling correlation between human expansion and vanishing mammals.

"We consistently find very large rates of extinction in areas where there had been no contact between wildlife and primitive human races, and which were suddenly confronted by fully developed modern humans (Homo sapiens). In general, at least 30% of the large species of animals disappeared from all such areas,” says Aarhus professor Jens-Christian Svenning, who also worked on the study.

So, where have all the giant kangaroos, giant wombats and marsupial lions gone?

The Danish research points to one stark conclusion.

They likely met the end of the evolutionary line at the tip of a hunter's spear.

And an even more chilling forecast for today's large animal population.

The study notes:

The results also draw a straight line from the prehistoric extinction of large animals via the historical regional or global extermination due to hunting (American bison, European bison, quagga, Eurasian wild horse or tarpan, and many others) to the current critical situation for a considerable number of large animals as a result of poaching and hunting (e.g. the rhino poaching epidemic).

Scientific Name: Rafetus Swinhoei
Common Name: Red River Giant Softshell Turtle
Category: Turtle
Population: 4 known individuals
Threats To Survival: Hunting for consumption and habitat destruction and degradation as a result of wetland destruction and pollution

Scientific Name: Callitriche pulchra
Common Name: None
Category: Freshwater plant
Population: Unknown (declining)
Threats To Survival: Exploitation of the species' habitat by stock, and modification of the pool by local people

Scientific Name: Diospyros katendei
Common Name: None
Category: Tree
Population: 20 individuals, one population
Threats To Survival: High pressure from communities for agricultural activity, illegal tree felling, habitat degradation due to alluvial gold digging and small population

Scientific Name: Pristis pristis
Common Name: Common Sawfish
Category: Sawfish
Population: Unknown (declining)
Threats To Survival: Exploitation - has removed the species from 95% of its historical range

Scientific Name: Rhinopithecus avunculus
Common Name: Tonkin Snub-Nosed Monkey
Category: Primate
Population: < 200 individuals
Threats To Survival: Habitat loss and hunting. Known from only a few records in small area of habitat ( less than 10km2)